Ibarra et al. (2014) have presented an interesting paper on the Cotham Marble, an enigmatic microbialite from the Rhaetian Penarth Group of SW England, and an iconic piece of British stratigraphy. They have re-interpreted some aspects of our earlier work (Wright and Mayall 1981) in which we tried to be amongst the first researchers to apply an ethological approach to decipher an ancient microbial texture. That paper (Wright and Mayall 1981) was restricted editorially with respect to its content requiring a second one to illustrate the microbial microtextures we felt were critical to understanding the morphogenesis of the limestone (Mayall and Wright 1981). In addition to challenging previously published work, Ibarra et al. (2014) use the Cotham Marble to identify evidence for the late Triassic mass extinction event, thus substantially broadening the importance of this unit for the wider readership. However we would like to take this opportunity to question a number of their conclusions, in particular using the Cotham Marble as an indicator of a mass extinction event and the role of Microtubus communis in forming the Cotham Marble.

Mayall and Wright question interpretations in our microfacies analysis of the Cotham Marble microbialites (Ibarra et al. 2014) in which we primarily highlight previously overlooked aspects of Cotham Marble microbialite formation. They are specifically unconvinced about the Cotham Marble’s potential relevance to the end-Triassic mass extinction and our interpretation that Microtubus is not integral to the formation of the dendrolitic microbialite phases. Here we address Mayall and Wright’s comments under the same headings in which they present them.